Marcus Rashford talks about scoring in his fourth straight game for Man United as they close the gap on the Premier League's top four.

Manchester United are hopeful that forward Marcus Rashford will be fit for Friday's FA Cup tie against Arsenal on Friday despite suffering a knee injury in the win over Brighton, sources have told ESPN FC.

Rashford, 21, scored in the 2-1 victory at Old Trafford on his 150th United appearance but fell awkwardly after a challenge from Martin Montoya in the second half.

After reporting stiffness in his knee, he will be assessed by United medical staff at Carrington before a decision is made about whether he can face Arsenal in the fourth round at the Emirates.

Rashford -- who has scored in his last four league games -- had been able to carry on following the collision before being replaced by Matteo Darmian, and United hope he will be able to play some part.

Caretaker manager Ole Gunnar Solskjaer made nine changes for the third round tie against Reading, and he will have to decide whether to rotate his squad with a Premier League game against Burnley coming just four days after the trip to the Emirates.

Romelu Lukaku and Alexis Sanchez, both substitutes against Brighton, are expected to start while Eric Bailly and Juan Mata are also in contention. Luke Shaw should also be available after missing the Brighton game because of illness.

Meanwhile, midfielder Scott McTominay has signed a new contract that will keep him at United until 2023.

McTominay had a breakthrough campaign last season, playing 23 times for the first team, and has played eight times this season, featuring twice under Solskjaer.

"Manchester United has been my life since the age of five and playing for the club I've always supported is all I've ever wanted to do," he said.

"I'm still young and I'm learning all the time from the manager, his coaching staff and from the world-class players in the squad. I can't wait to continue my progress at this great club."